HIV-1/2 antibody testing includes screening tests and supplemental tests.
A negative screening test results in a negative HIV-1/2 antibody report and is seen in individuals who are not infected with HIV, but a screening test can also be negative in recently infected individuals who are in the window period.
In case of a positive reaction, repeat the test with the original reagent and another reagent of a different principle or a different manufacturer, or another two reagents of a different principle or a different manufacturer, and if both reagents show a negative reaction in the repeat test, the test is HIV antibody negative; if one or both reagents show a positive reaction, a supplemental HIV antibody test is required. If no HIV-specific band is generated in the supplemental test, the test is reported negative for HIV-1/2 antibody.
If there is no progression of the band pattern or a negative reaction, the test will be reported as negative. If the band pattern progresses during the follow-up period and meets the criteria for determining HIV antibody positivity, the test will be reported as HIV antibody positive, and if the band pattern still does not meet the criteria for positivity, follow-up will continue until 8 weeks. If the band pattern does not progress or is negative, the patient will be reported as negative; if the HIV-positive diagnostic criteria are met, the patient will be reported as positive; if the positive criteria are not met, the patient will be followed up or not. If the HIV-1/2 antibody is positive by the supplemental test, the HIV-1/2 antibody positive confirmation report will be issued, and counseling, confidentiality and reporting will be done according to the regulations.
For those with a clear HIV epidemiological history and positive screening test, quantitative HIV nucleic acid testing can be performed as early as possible to help confirm the diagnosis if the supplemental test is inconclusive.
Viral load measurement Recommended frequency of viral load testing: For patients who have been on antiviral therapy for more than 6 months and have sustained viral suppression, testing can be performed every 6 months. within 6 months of HAART or if viral load suppression is unsatisfactory or the treatment regimen needs to be adjusted, the frequency of viral load testing should be determined by the clinician according to the patient’s specific situation. If possible, testing is recommended once a year for untreated asymptomatic HIV-infected patients, and once every 4 to 8 weeks before initial HAART treatment or adjustment of treatment regimen, and at the beginning of initial treatment or adjustment of treatment regimen to detect virologic failure as early as possible. After the viral load is below the lower limit of detection, testing should be performed every 3-4 months. For patients with good compliance, sustained viral suppression for more than 2-3 years, and stable clinical and immunological status, testing can be performed every 6 months, but HIV load testing is recommended every 3 months if HIV-related clinical symptoms or hormonal or antitumor chemotherapeutic drugs are present.
CD4+ T-lymphocyte testing It is generally recommended that asymptomatic HIV-infected patients with CD4+ T-lymphocyte counts >350 cells/μL should be tested every 6 months; patients who have received HAART should be tested every 3 months during the first year of treatment and every 6 months for patients who have been on treatment for more than a year and have stable disease. For patients whose viruses are fully suppressed after antiviral therapy and whose CD4+ T lymphocyte counts are stable for a long time, frequent testing is not necessary: patients with CD4+ T lymphocyte counts between 300 and 500 cells/μL are recommended to be tested every 12 months; patients with >500 cells/μL can be selectively tested for CD4+ T lymphocyte count. However, periodic CD4+ T lymphocyte count testing is required again for patients who have had a virologic breakthrough, patients who have developed AIDS-related clinical symptoms, and patients receiving treatment that may lower their CD4+ T lymphocyte count.
HIV genotypic resistance testing When antiviral treatment viral load decline is unsatisfactory or when antiviral treatment has failed and a change in treatment regimen is required; before proceeding to antiviral treatment (if conditions permit). For those who have failed antiviral therapy, resistance testing is performed when viral load is >400 copies/mL and antiviral drugs have not been discontinued; genotypic resistance testing is required within 4 weeks of drug discontinuation if drugs have been discontinued.